The requirements specification of a liquid crystal display device, which displays images on a liquid crystal display panel, may include assurance of wide temperature range operation, especially in on-board use, for example. To assure wide temperature range operation, it is desired to keep image quality at low temperature.
On the other hand, reducing power consumed by a liquid crystal display device may be desired. Reducing power consumption is important especially when a liquid crystal display device is incorporated in a system which uses a power storage device (e.g. battery) as the power supply.
One known approach for reducing power consumption in a liquid crystal display device is controlling the precharge operation of a source line in response to the value of image data (data indicating the grayscale level of each pixel). In this technique, execution/non-execution of the precharge operation is selected, most typically, in response to the value of the most significant bit of image data. When a 256-level grayscale is displayed on each pixel, for example, the precharge operation is not performed for image data indicating a grayscale level of “127” or less (in this case, the most significant bit of the image data is “0”), and the precharge operation is performed for image data indicating a grayscale level of “128” or more (in this case, the most significant bit of the image data is “1”). A technique in which the precharge level is controlled on the grayscale level indicated by image data is also known in the art; such technique is disclosed in Japanese Patent Application Publication No. 2010-102146 A.
According to an inventor's study, however, the control of the source line precharge operation in response to the grayscale level indicated in image data may cause display quality deterioration of a liquid crystal display device at low temperature.